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Fri, 10 Jul 2026 09:44:28 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wiEKx-00000007Yxj-3wpY; Fri, 10 Jul 2026 13:44:27 -0300 Date: Fri, 10 Jul 2026 13:44:27 -0300 From: Jason Gunthorpe To: Stanislav Kinsburskii Cc: airlied@gmail.com, akhilesh@ee.iitb.ac.in, akpm@linux-foundation.org, corbet@lwn.net, dakr@kernel.org, david@kernel.org, decui@microsoft.com, haiyangz@microsoft.com, kees@kernel.org, kys@microsoft.com, leon@kernel.org, liam@infradead.org, lizhi.hou@amd.com, ljs@kernel.org, longli@microsoft.com, lyude@redhat.com, maarten.lankhorst@linux.intel.com, mamin506@gmail.com, mhocko@suse.com, mripard@kernel.org, nouveau@lists.freedesktop.org, ogabbay@kernel.org, oleg@redhat.com, rppt@kernel.org, shuah@kernel.org, simona@ffwll.ch, skhan@linuxfoundation.org, surenb@google.com, tzimmermann@suse.de, vbabka@kernel.org, wei.liu@kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH v7 8/8] drm/gpusvm: Use hmm_range_fault_unlocked_timeout() for range faults Message-ID: <20260710164427.GW118978@ziepe.ca> References: <178345345668.660027.2952911919681614557.stgit@skinsburskii> <178345366389.660027.12986386801605494596.stgit@skinsburskii> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <178345366389.660027.12986386801605494596.stgit@skinsburskii> On Tue, Jul 07, 2026 at 12:47:43PM -0700, Stanislav Kinsburskii wrote: > Several GPU SVM paths take mmap_read_lock() only to call hmm_range_fault(), > then retry -EBUSY until HMM_RANGE_DEFAULT_TIMEOUT expires. Those paths use > MMU interval notifiers whose mm matches the mm that was locked for the HMM > fault. > > Use hmm_range_fault_unlocked_timeout() for those faults and pass the > remaining retry budget to HMM. The helper owns mmap_lock acquisition and > refreshes range->notifier_seq internally for each retry, while GPU SVM > keeps its existing driver-lock validation with mmu_interval_read_retry() > after a successful fault. > > Leave drm_gpusvm_check_pages() on hmm_range_fault() because that path is > called with the mmap lock already held by its caller. > > Signed-off-by: Stanislav Kinsburskii > --- > drivers/gpu/drm/drm_gpusvm.c | 52 ++++++------------------------------------ > 1 file changed, 7 insertions(+), 45 deletions(-) Reviewed-by: Jason Gunthorpe > - mmap_read_unlock(range->gpusvm->mm); > + err = hmm_range_fault_unlocked_timeout(&hmm_range, > + max_t(long, timeout - jiffies, 1)); Same remark about max_t Jason